The enzyme transglutaminase (TGase (R-glutamylpeptide: amine gamma-glutamyl-transferase EC 2.3.2.13) has been reported to catalyze the formation of dipeptide bonds between the glutamine and lysine residues in polypeptides via covalent coupling of the gamma carboxyamide group of peptide bound glutamine residues with an epsilon amino group of peptide bound lysine residues (Folk, et al., Adv. Enzymol., 38:109-191 (1973)). The TGase in hair follicles of humans is reported to be distinct from the epidermal TGase (Ogawa, et al., J. Invest. Dermatol., 68:32-35 (1977)). TGase is also said to be found in hair follicles of guinea pigs (Chung, et al., Proc. Natl. Acad. Sci., U.S.A. 69:303-307 (1972)); of rats (Peterson, et al., Biochim. Biophys. Acta, 657:268-276 (1981)); and of sheep (Harding, et al., Biochemistry, 11:2858-2863 (1972)).
In addition to direct detection of TGases in follicles, the dipeptide gamma-glutaminyl (lysyl) crosslinks have also been identified in the proteins of the medulla of the hair shaft and the inner root sheath of guinea pig follicle which adjoins the cortical cells of the hair (Harding, et al., Biochemistry, 10,(4):624-630 (1971). These dipeptide bonds are said to stabilize structural proteins imparting structural integrity to the medulla and to provide resistance to proteolytic attack by microorganisms (Goldsmith, L. A., "Hair Follicle Transglutaminases and the Formation of -(Glutamyl) Cross Links in Hair Research", pp. 290-35, 1981, Ed. by Orfanos Montagna, and Stuttgen, Springer Verlag Berlin Heidelberg).
The enzyme activity of TGase is reported to be increased in actively growing versus quiescent regions of hair growth (Hattori, et al., J. of Dermatology, 10:45-54 (1983)). It has not been known what impact, if any, inhibition of transglutaminase activity would have on the rate or character of hair growth since its activity on hair shaft proteins is confined to the latter stages of hair growth involving the secondary or posttranslational modifications of previously synthesized shaft proteins.
U.S. Pat. Nos. 4,912,120 and 4,929,630 Castelhano et al. describe various 3,5-disubstituted-4,5-dihydroisoxazoles as inhibitors of transglutaminase useful for administration to mammals suffering from a disease characterized by elevated transglutaminase activity, such as acne, psoriasis, or cataracts.
It has previously been proposed to alter the rate and character of hair growth by applying to the skin inhibitors of certain enzymes such as inhibitors of 5-alpha-reductase or of ornithine decarboxylase, or such antiandrogen materials as cytoplasmic androgen receptor binding agents, as described in U.S. Pat. Nos. 4,720,489 and 4,885,298. Moreover, it has been theorized that other enzymes, including gamma-glutamyl transpeptidase, are involved in various stages of hair follicle formation or of hair growth, but the relation between the various enzymes and the reactions which they control, as well as their effect upon each other and upon hair growth, has not been fully understood, as appears from Richards et al., Cancer Research, 42:4143-4152 (1982); DeYoung et al, Cancer Research, 38:3697-3701 (1978); and Chase, Physiolo. Zool., 24:1-8 (1951).
It has now been found that topical application to the skin of a normal mammal (including human), i.e., a mammal free from a disease characterized by elevated transglutaminase activity, of a composition containing an inhibitor of transglutaminase, is effective to reduce the rate and alter the character of mammalian hair growth, particularly androgen-stimulated hair growth. By "alter the character" is meant that it renders the hair, particularly androgen-stimulated hair growth, softer and downier and/or more easily cut. Particularly preferred is a process in which the inhibitor is a specific, non-competitive inhibitor of transglutaminase such as 3-bromo-5-(N-benzyloxycarbonyl-1-phenylalanamido-methyl)-4,5-dihydroisoxaz ole (BBD) 5-(N-benzyloxycarbonyl-L-para-tyrosinamidomethyl)-3-bromo-4,5-dihydroisoxa zole, 5-(N-2-(s)-6-methoxy-2-naphthyl)-propionyl)-L-p-tyrosinamidomethyl-5-(s) -3-bromo-4,5-dihydroisoxazole or other 3,5-disubstituted-4,5-dihydroisoxazole inhibitor as described in U.S. Pat. Nos. 4,912,120 and 4,929,630, the descriptions of which are hereby incorporated by reference in the present application.
The composition of the present invention contains, in addition to the inhibitor, a non-toxic dermatologically acceptable vehicle or carrier which is adapted to be spread upon the skin including the follicles. The concentration of the inhibitor in the composition may be varied over a wide range up to a saturated solution, preferably from 0.1 to 20% by weight or even more; the reduction of hair growth increases as the amount of inhibitor applied increases per unit area of skin. The maximum amount effectively applied is limited only by the rate at which the inhibitor penetrates the skin. Generally, the effective amounts range from 10 to 2500 micrograms or more per square centimeter of skin. In the case of BBD inhibitor, which is hydrophobic, non-aqueous vehicles, such as those based on an alcohol, e.g., ethyl alcohol or benzyl alcohol, are preferred.
The following specific example is intended to illustrate more clearly the nature of the present invention without acting as a limitation upon its scope.